ANSI PWF-2015 pdf free download
ANSI PWF-2015 pdf free download.PWF Permanent Wood Foundation Design Specifcation with Commentary.
The basic design and construction requirements for permanent wood foundation (PWF) systems are set forth in this Permanent Wood Foundation Design Specification. Criteria for materials, preservative treatment, soil characteristics, environmental control, design loads, and structural design are included. Where requirements are based on nationally recog- nized standards and specifications, these standards and specifications are referenced without elaboration. This Specification is not intended to preclude the use of materials, assemblies, structures, or designs not meeting the criteria herein, where it is demonstrated by analysis based on recognized theory, full scale or prototype loading tests, studies of model analogues, or extensive experience in use that the material, assem- bly, structure, or design will perform satisfactorily in its intended use.
The quality of wood products and fasteners, and the design of supporting members and connections shall comply with the requirements of the building code under which the foundation is designed and the standards specified herein. 1.3 Terminology ALLOWABLE STRESS DESIGN (ASD). A method of proportioning structural members and their connec- tions such that computed stresses do not exceed speci- fied allowable stresses when the structure is subjected to appropriate load combinations (also called working stress design). BACKFILL HEIGHT. The height of soil backfill measured from the bottom of the stud to the exterior ground surface at any particular point. For a crawl space with a trenched footing, backfill height is the difference between exterior and interior ground sur- faces at any particular point. COMPOSITE FOOTING. Footing which is com- prised of a treated wood footing plate and a granular drainage layer consisting of gravel, coarse sand, or crushed stone. DEEP FROST PENETRATION. Frost penetrations that are typically in the range of 4 feet or greater. END WALL. Exterior PWF wall oriented parallel to floor joists. GRANULAR DRAINAGE LAYER. A continuous layer of gravel, crushed stone or coarse sand used to drain the bottom of the foundation and to distribute the load from the footing to the soil.
2.1 Framing Framing used in the PWF system shall be lumber in accordance with USDOC PS 20 and shall bear the stamp of an approved grading agency or inspection bureau which participates in an accreditation program, such as the American Lumber Standard (ALS) pro- gram or equivalent. 2.2 Sheathing Sheathing used in the PWF system shall be plywood manufactured with all softwood veneers, bonded with exterior adhesive (Exposure 1 or Exteri- or), and grademarked indicating conformance with USDOC PS 1, USDOC PS 2, or applicable code eval- uation reports. 2.3 Preservative Treatment 2.3.1 General All exterior foundation wall framing and sheathing (except the upper top plate); all interior bearing wall framing and sheathing, posts or other wood supports used in crawl spaces; all sleepers, joists, blocking and plywood subflooring used in basement floors; and all other plates, framing and sheathing in contact with the ground or in direct contact with concrete shall be pres- sure treated with preservatives. Treatment shall be in accordance with AWPA U1: Commodity Specification A, Section 4.2 Lumber and Plywood for Permanent Wood Foundations; UC4B Retentions and AWPA T1, Processing and Treatment Standard; Section 8, Special Requirements for Permanent Wood Foundation Mate- rial. Exceptions: 1. Members 8 in. or more above finish grade are not required to be preservative treated. 2. Untreated lumber may be used in interior load-bearing walls where such walls are sup- ported directly on top of a treated floor sys- tem.
3.1 Soil Types Soil types shall be as determined by the authority having jurisdiction (AHJ) unless a geotechnical inves- tigation report is provided to and approved by the AHJ. Soil types classified under the Unified Soil Clas- sification System shall be in accordance with ASTM D 2487. 3.2 Soil Structure Characteristics 3.2.1 Design Properties of Soils Design properties shall be based on the minimum design properties required by the AHJ unless an ap- proved geotechnical investigation report is provided. 3.2.2 Soils With Good to Medium Drainage Soils classified as GW, GP, SW, SP, GM, SM, GC, SC, ML, and CL which are characterized by good to medium drainage characteristics, shall be permitted for use with PWF basements or crawl space applica- tions provided the following requirements are satis- fied: 1. the lot grading complies with 4.1.1; 2. the backfill is free of voids, organic matter, or chunks of clay; 3. polyethylene sheeting is applied under the basement floor and on exterior walls and complies with 4.1.3 and 4.1.6 respectively; 4. for basements, a sump is provided and com- plies with 4.1.4; and, 5. for basements, drainage underneath the foun- dation complies with 4.1.2.
